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Title: Post-glacial coupling of the Australasian monsoon and teleconnections to the North Atlantic: new insights from Indonesian speleothems
Authors: Griffiths, ML
Drysdale, RN
Gagan, MK
Zhao, JK
Ayliffe, LK
Hellstrom, JC
Hantoro, WS
Frisia, S
Feng, YX
Cartwright, I
St Pierre, E
Fisher, M
Suwargadi, B
Keywords: Australia
Tropical regions
Trace amounts
Southern Oscillation
Issue Date: 15-May-2009
Publisher: GNS Science
Citation: Griffiths, M., Drysdale, R., Gagan, M., Zhao, J.-x., Ayliffe, L., Hellstrom, J., Hantoro, W., Frisia, S., Feng, Y-x., Cartwright, I., St Pierre, E., Fischer, M., & Suwargadi, B. (2009). Post-glacial coupling of the Australasian monsoon and teleconnections to the North Atlantic: new insights from Indonesian speleothems. Paper presented at the Past Climates meeting, Wellington New Zealand, May 15-17, 2009.
Abstract: The Australasian monsoon system orchestrates rainfall variability and terrestrial productivity in the densely populated region of the tropical Indo-Pacific. A clear understanding of the dominant mechanisms governing its variability has been difficult to resolve, partly because we currently lack high-resolution proxy records of past monsoon behaviour, particularly for the southern tropics. Here we provide a radiometrically dated reconstruction of Australian-Indonesian summer monsoon (AISM) rainfall based on oxygen isotopes and trace element data in stalagmites from southern Indonesia. The multi-proxy records are tied to age-depth models constructed from 62 TIMS and MC-ICP-MS U-series ages, covering the period 0 to 12.6 ka B.P. The record shows that the AISM was anti-phased with the East Asian summer monsoon (EASM) on orbital to millennial-centennial timescales over the past 12.6 ka. At the orbital-scale, local summer insolation was an important driver of opposing changes in AISM and EASM rainfall. However, a slight mismatch between the AISM and insolation from 9 to 11 ka B.P. is concurrent with the sharp rise in eustatic sealevel, which apparently increased the supply of northwesterly summer monsoon moisture to the Indonesian maritime continents. At millennial-centennial timescales, the oxygen isotope and trace element records show that periods of weakened North Atlantic meridional overturning circulation and cooling, including the Younger Dryas cold stage, are in phase with sharp increases in AISM rainfall. The connection between the AISM and a cooler North Atlantic is probably due to enhanced outflow from the Asian winter monsoon and associated southward migration of the intertropical convergence zone. These interhemispheric connections were dominant until ~6.5 ka, when the El Niño-Southern Oscillation became the governing influence on AISM variability.
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